1. Field of the Invention
The present invention relates to aircraft lift generating mechanisms, and more particularly, to aircraft lift generating mechanisms which include a plurality of airfoils driven in a single direction around an oval-shaped path.
2. Description of the Prior Art
A number of different devices have been proposed for generating lift by causing a plurality of airfoils to be rotated in a single direction through an oval path.
U.S. Pat. No. 4,166,595 (Ango) discloses a variable lift advancing wing aircraft which includes a plurality of independant airfoil sections coupled together by a chain and driven in a single direction through a rotary path. A complex mechanical arrangement is provided to deform the airfoil into a highly cambered lift-generating configuration as each airfoil is translated across an upper horizontal path segment of the oval-shaped path. As each airfoil is translated beyond the upper horizontal section of the oval-shaped path, the camber of the airfoil is permitted to return to its undeflected, less highly cambered configuration in which very little lift is generated. As each airfoil is translated rearward along a lower horizontal path segment, a small amount of negative lift is produced which lessens the net overall lift. The angle of incidence of each airfoil is maintained nearly constant at a zero angle as the airfoil is translated forward across the upper horizontal path segment and rearward across the lower horizontal path segment. A highly complex arrangement of mechanical elements is required to implement the complex variable lift advancing wing aircraft disclosed by Ango.
U.S. Pat. No. 4,113,205 (Shaw) discloses an aerodynamic lifting mechanism which includes a plurality of airfoils mounted on two continuous toothed belts. In the non-lift-generating mode of operation, each of the plurality of symmetrical airfoils is maintained at a zero angle of incidence such that a zero net lift is produced as the airfoils are continuously rotated in a single direction through an oval path. The leading edge of each symmetrical airfoil is continuously advanced in a single direction. When the pilot of the Shaw device desires to produce positive lift, he activates a flight control mechanism which increases the angle of incidence of the airfoils to provide a controllable amount of net lift.